Applicability of local climate zones in assessing urban heat risk - a survey of coastal city

Abstract

Efficient and accurate assessments of urban heat risk have become crucial as climate warming and rapid urbanization have led to frequent urban heat wave events, which pose a significant threat to the heat health of urban populations. The local climate zone framework for assessing urban heat islands is widely used in urban resilience and development assessments because of its simple and readable standardized building types, and it shows great potential for urban heat risk identification. Although some studies have been conducted on heat risk maps based on the LCZ framework, its applicability to heat risk assessment in coastal cities requires further validation. In this study, we employed machine learning and the Hazard-Exposure-Vulnerability- Adaptability system to generate LCZ and heat risk maps for the main urban area of Dalian. On the basis of the improved LCZ map, the applicability of the LCZ framework in characterizing urban heat risk in coastal cities and its influencing factors were explored. The results show that the LCZ-based heat risk distribution was significantly influenced by the unique mountain and sea pattern of Dalian, the type of LCZ for heat risk extremes varied among cities, and the LCZ framework cannot directly characterize urban heat risk. Secondly, the three-dimensional LCZ data has the potential to replace LST data as a heat hazard indicator for heat risk assessment. The study suggests that scientists should be cautious when using LCZs to assess the heat risk of a city or region, and that cities with complex topography should give due consideration to natural geographic indicators. Additionally, the LCZ map drawn at the block scale enhances the comprehensibility of climate risk responses for urban planners and provide a more targeted reference for future urban regeneration and climate planning.